Geo-synchronous satellite systems and point-to-point communication systems must operate in the presence of interfering signals operating at the exact same frequencies. The presence of these interfering satellite signals reduces signal quality and commensurately degrades the spectral efficiency that operators of very small aperture terminals (VSAT) can realize over geo-synchronous satellite networks. A terminal designed to operate at a spectral efficiency of 1.5 bits per second per Hz may be reduced to less than 0.5 bits per second per Hz when operating under adjacent satellite interference. Such interference triples the operational costs, making data services unprofitable, particularly in mobile applications.
State of the art solutions utilize two separate apertures that move together and permit a different aspect ratio when near the equator as compared to northern latitudes. Such systems suffer from reduced performance when the narrow dimension of the antenna is aligned with the arc of the geosynchronous satellite. The beam pattern of such antenna changes slightly, but is largely fixed and cannot be adjusted dynamically to cancel adjacent satellite interference signals. Antennas in mobile applications such as aviation, trucking, and shipping are limited in size, which further limits options for overcoming adjacent satellite interference.
Some existing systems include an oversized antenna that provides good spectral efficiency, but with a huge installation footprint and weight. Such antenna is a mechanically phased array but has a fixed beam pattern that cannot be adjusted to improve adjacent satellite interference.